Drug & supplement interaction

Transfer Factor + Carbidopa

Carbidopa brand name: Lodosyn.

No Known Interaction
The bottom line No known interaction

We found no known interaction between Transfer Factor and Carbidopa in our sources. Absence of a documented interaction is not the same as proven safety, and does not guarantee one does not exist. Do not start, stop, or change a medication or supplement based on this page; confirm with your pharmacist or doctor first. Additionally, although there is no interaction, the two are separately associated with some of the same side effects, which would make a new symptom harder to attribute to one or the other.

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Interaction report

Transfer Factor and Carbidopa

We checked these two against our interaction database. Here is what we found.

No Known Interaction Found

We did not find a documented interaction between Carbidopa and Transfer Factor in our sources. This does not guarantee that the combination is completely free of risk — there is often limited research on supplements and herbal products, especially around drug interactions.

Worth understanding: our licensed dataset holds no drug-interaction record for Transfer Factor at all — not against Carbidopa, and not against any other medication we track. This verdict therefore rests on the absence of any recorded data, not on research that looked at this combination and found nothing. We cannot rule an interaction out.

If you decide to take both, the practical routine is simple: add one new thing at a time and note the date you started it. If the combination is going to disagree with you, it usually shows in the first days to a couple of weeks — and a start date turns “I’ve been feeling off” into something a pharmacist can actually work with. Do not stop a prescribed medicine on your own.

Always talk with your pharmacist or doctor before making changes to your medications or supplements, particularly if you take several medications or have an ongoing health condition.

Transfer Factor safety at a glance

Transfer Factor overall Use caution Generally well tolerated in studies, but long-term safety and product quality are not well established.
Pregnancy Avoid Safety has not been established, so it is best avoided during pregnancy.
Breastfeeding Avoid Not enough safety information exists, so avoid while breastfeeding.

Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

Still wondering about combining Carbidopa and Transfer Factor? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
What to actually watch for

No Interaction Found — But Data Suggests Transfer Factor and Carbidopa May Share Several of the Same Side Effects

This is not an interaction. Neither one changes how your body handles the other, and nothing here says they react together. What our sources do show is that each has separately been linked to the effects below — so taking both can make those effects more likely to turn up, and harder to pin on one or the other if they do.

  • Swelling Additional detail

    Transfer Factor

    “Orally or parenterally, transfer factor seems to be well tolerated. Adverse effects may include fever. Parenterally, transfer factor can cause nausea, fatigue, and tenderness, pain, and swelling at the injection site.”

    Transfer Factor · Natural Medicines adverse-effect record, reported in acne.

    6 sources cited
    1. 350. Jones JF, Minnich LL, Jeter WS, et al. Treatment of childhood combined Epstein-Barr virus/cytomegalovirus infection with oral bovine transfer factor. Lancet 1981;2:122-4. PubMed
    2. 1445. Louie E, Borkowsky W, Klesius PH, et al. Treatment of cryptosporidiosis with oral bovine transfer factor. Clin Immunol Immunopathol 1987;44:329-34. PubMed
    3. 1507. Fudenberg HH. Transfer factor: past, present and future. Annu Rev Pharmacol Toxicol 1989;29:475-516. PubMed
    4. 3062. Miller LL, Spitler LE, Allen RE, Minor DR. A randomized, double-blind, placebo-controlled trial of transfer factor as adjuvant therapy for malignant melanoma. Cancer 1988;61:1543-9. PubMed
    5. 3063. Bukowski RM, Deodhar S, Hewlett JS, Greenstreet R. Randomized controlled trial of transfer factor in Stage II malignant melanoma. Cancer 1983;51:269-72. PubMed
    6. 7562. Lloyd AR, Hickie I, Brockman A, et al. Immunologic and psychologic therapy for patients with chronic fatigue syndrome: a double-blind, placebo-controlled trial. Am J Med 1993;94:197-203. PubMed

    “Parenterally, transfer factor may cause tenderness, pain, and swelling at the injection site.”

    Transfer Factor · Natural Medicines adverse-effect record, reported in pain.

    4 sources cited
    1. 3062. Miller LL, Spitler LE, Allen RE, Minor DR. A randomized, double-blind, placebo-controlled trial of transfer factor as adjuvant therapy for malignant melanoma. Cancer 1988;61:1543-9. PubMed
    2. 7562. Lloyd AR, Hickie I, Brockman A, et al. Immunologic and psychologic therapy for patients with chronic fatigue syndrome: a double-blind, placebo-controlled trial. Am J Med 1993;94:197-203. PubMed
    3. 7799. Fog T, Pedersen L, Raun NE, et al. Long-term transfer-factor treatment for multiple sclerosis. Lancet 1978;1:851-3. PubMed
    4. 78809. Fernandez, O., Diaz, N., Morales, E., Toledo, J., Hernandez, E., Rojas, S., Madriz, X., and Lopez, Saura P. Effect of transfer factor on myelosuppression and related morbidity induced by chemotherapy in acute leukaemias. Br.J.Haematol. 1993;84(3):423-427 PubMed

    Carbidopa

    Listed in the ADVERSE REACTIONS section of the FDA label for Carbidopa. Read the label on DailyMed ›

  • Tiredness Additional detail

    Transfer Factor

    “Parenterally, fatigue has been reported for up to 4 hours in a patient using transfer factor.”

    Transfer Factor · Natural Medicines adverse-effect record, reported in fatigue.

    1 source cited
    1. 78789. Thestrup-Pedersen, K., Grunnet, E., and Zachariae, H. Transfer factor therapy in mycosis fungoides: a double-blind study. Acta Derm.Venereol. 1982;62(1):47-53. DOI

    Carbidopa

    Listed in the ADVERSE REACTIONS section of the FDA label for Carbidopa. Read the label on DailyMed ›

  • Nausea Additional detail

    Transfer Factor

    “Parenterally, nausea has been reported in a patient following treatment with transfer factor”

    Transfer Factor · Natural Medicines adverse-effect record, reported in nausea and vomiting.

    1 source cited
    1. 78809. Fernandez, O., Diaz, N., Morales, E., Toledo, J., Hernandez, E., Rojas, S., Madriz, X., and Lopez, Saura P. Effect of transfer factor on myelosuppression and related morbidity induced by chemotherapy in acute leukaemias. Br.J.Haematol. 1993;84(3):423-427 PubMed

    Carbidopa

    Listed in the ADVERSE REACTIONS section of the FDA label for Carbidopa. Read the label on DailyMed ›

Reported for Transfer Factor but not commonly for Carbidopa: fever and acne.

Effects for Carbidopa come from the ADVERSE REACTIONS section of its FDA label; effects for Transfer Factor come from the Natural Medicines adverse-effect record, quoted above. Where a percentage is shown, it is the share of 52,609 voluntary FDA FAERS reports for Carbidopa that mention that effect — a reporting proportion, not an incidence rate and not evidence the drug caused it. Wording is matched across sources by our own clinical vocabulary, so treat this as a prompt to pay attention, not a diagnosis.

Everything else you take

See Every Supplement That Interacts With Carbidopa

This page covers Transfer Factor only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Carbidopa page lists 21 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Magnesium (major), 5-htp (moderate), Coffee Charcoal (moderate) and European Mandrake (moderate).

By severity: 2 major · 10 moderate · 9 minor.

From our pharmacist’s overview on the Carbidopa page

“Carbidopa (Lodosyn) keeps levodopa working in Parkinson's disease, so anything that blocks its absorption can cost real motor control, and two of the 21 supplements on this list do exactly that at a level rated major. Magnesium is the one that surprises people: in a human study it cut carbidopa absorption by 81 percent and levodopa's b…”

Reviewed by 2 · Jul 18, 2026

Open the Carbidopa interaction page

How much people look this up

Where Transfer Factor and Carbidopa Sit Against Everything Else

Out of every supplement and medication people look up on HelloPharmacist, here is where these two land this week — and which way each has been moving.

Supplement Transfer Factor
Steady interest

#845 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Carbidopa
Top half

#1,362 of 2,830 medications looked up here in the last 7 days

29 days ago today

Position among everything looked up on this site, not a measure of how commonly either one is used or how important it is. A supplement can climb this list because of a news story. It counts every request to the page, automated ones included, and nothing here identifies anyone.

Where does our data come from?
  • Source: the Natural Medicines (TRC Healthcare) clinical database — the evidence-graded professional reference for herb & supplement interactions.
  • Citation library: 103,510 references behind our interaction content, 65,311 of them resolved to verified PubMed/DOI sources. See every Transfer Factor reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 20, 2026. The Transfer Factor and Carbidopa records this page draws on were last updated July 10, 2026.
  • What “no known interaction” means: no documented interaction in the sources above — not a guarantee of safety. Supplements are studied far less than prescription drugs, so we say exactly what the evidence supports, and nothing more.
Data structure & sourcing designed and verified by .
Supplement

About Transfer Factor

What is Transfer Factor?

  • Immune support
  • Preventing colds and infections
  • Allergies
  • General wellness
  • Chronic viral conditions

Transfer factors are small immune molecules taken from cow colostrum or egg yolk and sold as supplements meant to boost or 'train' the immune system. Solid human evidence for the supplement products is limited, and quality varies widely between brands. Talk with your pharmacist or doctor before using one, especially if you have an immune condition.

Small immune molecules (peptides) extracted from sources such as cow colostrum or hen egg yolk · Capsules, tablets, powders

An interaction check asks whether these two react with each other — it does not ask whether Transfer Factor is a good idea for someone in your situation. Here is what our Transfer Factor record says about it on its own.

Transfer Factor: dosing

There is no official or standardized dose for transfer factor supplements. Because products differ in how they are made and how concentrated they are, the right amount is hard to define.The safest approach is to follow the directions on the product label and not exceed the recommended amount. They can help you decide if a product is appropriate and reasonable.

From our Transfer Factor monograph — the full record covers uses, side effects and every documented interaction.

Read the full Transfer Factor monograph & all interactions
Medication

About Carbidopa

What Is Carbidopa Used For?

Brand name: Lodosyn

Carbidopa tablets — sold under the brand name Lodosyn and as generic carbidopa — are used together with levodopa or carbidopa-levodopa to manage symptoms of Parkinson's disease, postencephalitic parkinsonism, and symptomatic parkinsonism that can result from carbon monoxide or manganese poisoning. Carbidopa is never used alone; it always works as a partner to levodopa-based therapy.

Lodosyn is specifically used when a patient taking carbidopa-levodopa isn't getting enough daily carbidopa from that combination, or when a patient needs the two drugs individually titrated (adjusted) rather than taken as a fixed combination. Adding carbidopa helps reduce the nausea and vomiting that levodopa often causes and allows lower doses of levodopa to be used.

Most-Reported Side Effects for Carbidopa

From FAERS, the FDA’s public side-effect reporting system (52,609 reports, all brands). Reports are voluntary and are not proof the drug caused the effect.

Fall 4,954 reports
Hallucination 4,554 reports
Tremor 3,533 reports
Dyskinesia 3,174 reports
Dizziness 2,837 reports
See full Carbidopa drug information
Keep checking

Other Drugs & Transfer Factor

Browse every other medication we’ve checked against Transfer Factor — both the ones with a known interaction and the ones without. Select any drug for the full detail.

0Major
0Moderate
0Minor
2,829No known interaction
No interaction 2,829 drugs checked — show the list
Evidence & sources

Transfer Factor References

The 49 references that drive our Transfer Factor monograph and interaction data, from the evidence-graded Natural Medicines (TRC Healthcare) database. Citations with a link open the study on PubMed or the publisher’s site.

  1. Jones JF, Minnich LL, Jeter WS, et al. Treatment of childhood combined Epstein-Barr virus/cytomegalovirus infection with oral bovine transfer factor. Lancet 1981;2:122-4. PubMed
  2. Steele RW, Myers MG, Vincent MM. Transfer factor for the prevention of varicella-zoster infection in childhood leukemia. N Engl J Med 1980;303:355-9. PubMed
  3. Louie E, Borkowsky W, Klesius PH, et al. Treatment of cryptosporidiosis with oral bovine transfer factor. Clin Immunol Immunopathol 1987;44:329-34. PubMed
  4. McMeeking A, Borkowsky W, Klesius PH, et al. A controlled trial of bovine dialyzable leukocyte extract for cryptosporidiosis in patients with AIDS. J Infect Dis 1990;161:108-12. PubMed
  5. Fudenberg HH. Transfer factor: past, present and future. Annu Rev Pharmacol Toxicol 1989;29:475-516. PubMed
  6. Lewis CJ. Letter to reiterate certain public health and safety concerns to firms manufacturing or importing dietary supplements that contain specific bovine tissues. FDA. Available at: www.cfsan.fda.gov/~dms/dspltr05.html.
  7. Miller LL, Spitler LE, Allen RE, Minor DR. A randomized, double-blind, placebo-controlled trial of transfer factor as adjuvant therapy for malignant melanoma. Cancer 1988;61:1543-9. PubMed
  8. Bukowski RM, Deodhar S, Hewlett JS, Greenstreet R. Randomized controlled trial of transfer factor in Stage II malignant melanoma. Cancer 1983;51:269-72. PubMed
  9. Bowden RA, Siegel MS, Steele RW, et al. Immunologic and clinical responses to varicella-zoster virus-specific transfer factor following marrow ransplantation. J Infect Dis 1985;152:1324-7.
  10. Sharma MK, Anaraki F, Ala F. Preliminary results of transfer factor therapy of persistant cutaneous leishmania infection. Clin Immunol Immunopathol 1979;12:183-90. PubMed
  11. Whyte RI, Schork MA, Sloan H, et al. Adjuvant treatment using transfer factor for bronchogenic carcinoma: long-term follow-up. Ann Thorac Surg 1992;53:391-6. PubMed
  12. Lloyd AR, Hickie I, Brockman A, et al. Immunologic and psychologic therapy for patients with chronic fatigue syndrome: a double-blind, placebo-controlled trial. Am J Med 1993;94:197-203. PubMed
  13. Spitler LE. Transfer factor therapy in the Wiskott-Aldrich syndrome. Results of long-term follow-up in 32 patients. Am J Med 1979;67:59-66.
  14. Roda E, Viza D, Pizza G, et al. Transfer factor for the treatment of HBsAg-positive chronic active hepatitis. Proc Soc Exp Biol Med 1985;178:468-75. PubMed
  15. Basten A, McLeod JG, Pollard JD, et al. Transfer factor in treatment of multiple sclerosis. Lancet 1980;2:931-4. PubMed

Medication overviews come from MedlinePlus (NIH); supplement label data from the NIH Dietary Supplement Label Database. Content is written and reviewed by licensed HelloPharmacist pharmacists — see our data sources and editorial standards.

Pharmacist Counseling Corner

Taking Transfer Factor and Carbidopa Together: Common Questions

Is it safe to take Transfer Factor with Carbidopa?
We do not list a known interaction between Transfer Factor and Carbidopa. That does not guarantee the combination is risk-free, so confirm with your pharmacist or doctor — especially if you take other medications or have a health condition.
Do Transfer Factor and Carbidopa have any of the same side effects?
Yes — our sources link each of them separately to 3 of the same effects. That is not an interaction: neither changes how your body handles the other. It does mean that if one of those effects turns up, it can be harder to tell which one is behind it. They are listed on this page with the source behind each.
Does Carbidopa interact with any supplements?
Yes. Carbidopa has documented interactions with 21 supplements in our database — Transfer Factor is not one of them. The Carbidopa interaction page linked on this page lists every one, ranked by severity.

Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy

Still Have a Question About Carbidopa and Transfer Factor?

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This information is for education only and is not a substitute for professional medical advice. Always check with your pharmacist or doctor before starting, stopping, or combining supplements and medications.